In this project we will transplant Nude/SCID mice with human bone marrow. Subsequently, we will transplant HLA matched various human cancers to variou sites. We will determine whether bone marrow derrived stem cells caarrying one reporter gene are migrating preferentially to areas of active cancers as in "healing wound". Since both tumor cells and the stem cells will carry a different reporter gene, we will be able to determine whether fusion occured. If fusion occur to any clinical significance we will try to understand its mechanism, receptor and block it. We will also determine what makes normal bone marrow stem cells migrate into cancer and participate in carcinogenesis